Topic 4a - Cellular reproduction Flashcards Preview

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Flashcards in Topic 4a - Cellular reproduction Deck (51):
1

Prokaryotic cells divide how?

binary fission

2

Define gene.

sections of DNA that code for one product (protein)

3

Define chromatin.

uncondensed DNA - typical form in the cell

4

Define chromosome

Condensed form of DNA - easily divided evenly

5

Place in order from DNA double helix to chromosome...

DNA double helix -> DNA wound around histone proteins -> coiled DNA/histone beads -> coiled & looped DNA attached to protein scaffold -> folded chromosome

6

Ends of chromosomes are called...?

telomeres -

7

Centre of chromosome...?

centromere - links sister chromatids

8

How many chromosomes in a male?

23 (22 + X&Y)

9

In mitosis, what are the stages of interphase? Briefly describe each stage...

G1: cell growth & differentiation
S: synthesis of DNA; chromosomal duplication
G2: cell growth & preparation for cell division

10

What are the phases of mitotic cell division...?

prophase
metaphase
anaphase
telophase & cytokinesis

11

Describe the events in early & late prophase...

Early prophase - chromosomes condense; spindles begin to form; nuclear membrane begins to disappear
Late prophase - centrioles move to opposite poles; spindle microtubules attach to centromeres forming kinetochores; nucleolus & nucleus have almost disappeared

12

Describe the events in metaphase...

chromosomes & their centromeres attached to spindle fibres are lined up in the middle of the cell

13

Describe the events in early & late anaphase...

Early anaphase - centromeres split; half of the chromosomes move to one pole, half to the other pole
Late anaphase - chromosomes almost at respective poles; cell membrane begins to pinch at the center

14

Describe the events in telophase...

cell membrane completes constriction; chromosomes extend; nuclear envelope begins re-forming

15

Describe cytokinesis...

cytoplasm divides; parent cell becomes 2 daughter cells (diploid) with identical genetic information

16

Where are the 3 check points in cell division?

G1 -> S: is DNA intact & suitable for replication?
G2 -> M: DNA completely & accurately replicated?
metaphase -> anaphase: are all chromosomes attached to the spindle & aligned at the equator?

17

In cell differentiation, what are the 3 types of cells...? Give examples of each...

stem cells - give rise to other stem cells & other types of cells eg. stem to stem, & stem to neuron
other cells capable of dividing - give rise to only the same type of cell
fully differentiated cells - incapable of dividing eg. neuron cannot divide

18

Define haploid

n chromosomes

19

Define diploid

two complete sets of every gene (chromosomes) 2n chromosomes

20

Define allele. Give example

alternate forms of the same gene
eg. eye colour (brown or blue) both alleles code for 'eye colour'

21

T or F - homologous chromosomes can have different alleles?

true

22

Define sexual reproduction

combining genetic material from two organisms (same species)

23

If offspring contain genetic material from two parents, how do we avoid repeated doubling of genetic material each generation?

fusion of gametes (each containing n chromosomes)

24

Parental cells contain how many sets of chromosomes? (diploid or haploid?)

2n (diploid)

25

Gametes are diploid or haploid?

n (haploid)

26

Fertilised egg is diploid or haploid?

2n (diploid)

27

From 2n chromosomes, mitosis produces how many chromosomes?

2n

28

Somatic cells (non-sex cells) are...?

diploid

29

Sex cells are...?

haploid

30

What happens in prophase I of meiosis?

crossing over

31

What happens at metaphase I of meiosis?

homologue chromosomes align in the center of the cell

32

What are the sections of crossing over called?

chiasmata

33

What happens at anaphase I of meiosis?

mitotic spindles pull homologous chromosomes to opposite poles

34

Analogous to mitosis is...?

meiosis II

35

What are the sources of genetic variability?

- random shuffling of homologous chromosomes (2^23 = >8 million combinations)
- crossing over
- fusion of gametes (8 million x 8 million = 64 trillion unique combinations)

36

Haploid life cycle occurs in...?

protists, algae, fungi

37

Diploid life cycle occurs in...?

animals

38

Alternation of generations occurs in...?

plants

39

Define locus/loci...

specific position of a gene or DNA sequence on a chromosome

40

Define mutation...

stable & inheritable change in nucleotide sequence

41

Define homologous...

set of 1 maternal & 1 paternal chromosome that pair up inside a cell during meiosis

42

Define telomere...

repetitive nucleotide sequences at each end of a chromatid - protects chromosome from deterioration or fusion with other chromosomes

43

Define chromatid...

one copy of a duplicated chromosome joined by a centromere

44

Define karyotype...

complete set of chromosomes in the nucleus of a eukaryotic cell

45

Define autosome...

a chromosome that is NOT a sex chromosome

46

Define sex chromosome...

allosome - haploid

47

Define centriole...

organise mitotic spindles
completion of cytokinesis

48

Define kinetochore...

protein structure on chromatids where spindle fibres attach during cell division to pull sister chromatids apart

49

Define mitosis...

cell division into two genetically identical daughter cells

50

Define meiosis...

cell division necessary for reproduction in eukaryotes such a animals, plants, and fungi.

51

Define synapsis...

the pairing of two homologous chromosomes that occurs during meiosis